1. Field of the Invention
The present invention relates to wastewater treatment, particularly to an improved combined process vessel apparatus for separating oil, gas, and solids from influent produced water, such as the wastewater generated from oil and gas well drilling and production operations. More particularly, the present invention relates to an improved combined process vessel apparatus that features primary inlet separation, coalescing media and hydrocyclone separation in a single vessel, saving both platform space and piping.
2. General Background of the Invention
In the oil and gas well drilling industry, offshore platforms that are used in the drilling and production of oil and gas wells generate wastewater material that must be treated. This wastewater material is typically produced water that includes gas and droplets of oil. These droplets of oil must necessarily be removed from the waste stream before the treated water can be recycled or returned to the surrounding marine environment. Indeed, the oil must be removed sufficiently so that the water is clean enough to be discharged into the surrounding marine environment without adversely affecting marine plants and animals.
Patents have been issued that are directed to the concept of cleaning produced water in the oil and gas well drilling and production environment, including e.g., U.S. Pat. Nos. 5,681,458; 4,618,430; 4,428,841; 4,252,649; 4,372,757; and 3,893,318, each of which is incorporated herein by reference.
At times, hydrocyclones have been positioned downstream of the flowline that is discharged from an oil and gas separator. Numerous designs of hydrocyclone separators have been developed and utilized in the production of hydrocarbons from subterranean formations. Hydrocyclone separators are being utilized in more applications in hydrocarbon production due to increased environmental concerns regarding the discharge of oil with produced water into bodies of water. Examples of hydrocyclone separators are disclosed in the following patents, each of which is incorporated herein by reference: U.S. Pat. Nos. 4,237,006; 4,251,368; 4,544,486; 4,576,724; 4,464,264; and 4,683,061.
Other separate vessels that have been used to treat oily wastewater include, for example, gas flotation vessels, skim piles (see U.S. Pat. No. 3,893,918), and closed drain reflux skimmers.